Water cooler



FIG. 1 is a front perspective view of a water cooler showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a left side view thereof; and,

FIG. 6 is a rear view thereof. 

The ornamental design for a water cooler, as shown. 